1. Field of the Invention
The present invention relates to a battery field, and more particularly, to a lithium based thin film battery having an excellent manufacturing efficiency and an enhanced battery property.
2. Description of the Related Art
A current collector corresponds to a metal conductor connecting a cathode or an anode of a thin film battery to an external circuit or a load. A material to form the current collector may use a single metal, for example, gold (Au), platinum (Pt), copper (Cu), ruthenium (Ru), chrome (Cr), and the like, or may use a conductive oxide such as indium tin oxide (ITO). In general, a single noble metal such as Pt, Au, and the like may be used for a cathode current collector. Nickel (Ni), molybdenum (Mo), Cu, and the like may be used for an anode current collector.
Pt or Au shows a relatively stable thermal and chemical stability in a crystal growth temperature range of a cathode and thus, may be generally used for the cathode current collector. Cu, Ni, and the like have no reaction with lithium (Li) and thus, may be generally used for the anode current collector. Even though a noble metal such as Pt or Au has a relatively stable thermal and chemical stability in a growth temperature range of a thin film battery, the noble metal is relatively expensive. In addition, a magnetic metal such as Ni has a thickness constraint of a target and a relatively low deposition rate during a deposition process. Accordingly, a replacement cycle may become short, which may result in decreasing an operation rate of a sputtering equipment. Cu may be more easily oxidized in an atmosphere having a high temperature and a relatively large amount of humidity.
When a cathode current collector including a single kind of noble metal is used, a barrier layer may need to be used to prevent a material of a substrate attachment layer from being diffused to a cathode during a heat treatment process. Accordingly, a process efficiency may decrease. In addition, in an economical aspect, the noble metal may have a supply-and-demand issue due to a fluctuation in prices.